Question

I’m looking for a good way to take a set of objects and convert them to Excel format. I used VSTO in the past, but it was not well documented and I was not happy with many of the naming conventions and breaking changes.

I thought about maybe doing an XSLT transform, but don’t see any clean way to get from there to Excel. I saw something about going XSLT > HTML > Excel, but I dunno…html is such a loose standard I don’t trust it to produce consistent data transformations.

What do you recommend?

Answer 1

I use the code that can be found on The Code Project website.

It creates an xml file that Excel understands as an excel workbook. It’s quirky; when you open it, you get a message like this:

the file you are trying to open is in
a different format than specified by
the file extension

It opens fine though and you can then save it to a real excel format.

Looking at the code, it doesn’t look like it’d take much to create multiple worksheets (which I think is what you wanted to do). 🙂

Here’s the code if for some reason the link doesn’t load:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Reflection;
using System.Collections;

namespace myNamespace
{
    public class IOProcess
    {


        //http://www.codeproject.com/KB/dotnet/ExportToExcel.aspx?df=100&forumid=146533&exp=0&select=1357703
        public static void ExportToExcel(DataSet source, string fileName)
        {

            System.IO.StreamWriter excelDoc;

            excelDoc = new System.IO.StreamWriter(fileName);
            const string startExcelXML = "<xml version>\r\n<Workbook " +
                  "xmlns=\"urn:schemas-microsoft-com:office:spreadsheet\"\r\n" +
                  " xmlns:o=\"urn:schemas-microsoft-com:office:office\"\r\n " +
                  "xmlns:x=\"urn:schemas-    microsoft-com:office:" +
                  "excel\"\r\n xmlns:ss=\"urn:schemas-microsoft-com:" +
                  "office:spreadsheet\">\r\n <Styles>\r\n " +
                  "<Style ss:ID=\"Default\" ss:Name=\"Normal\">\r\n " +
                  "<Alignment ss:Vertical=\"Bottom\"/>\r\n <Borders/>" +
                  "\r\n <Font/>\r\n <Interior/>\r\n <NumberFormat/>" +
                  "\r\n <Protection/>\r\n </Style>\r\n " +
                  "<Style ss:ID=\"BoldColumn\">\r\n <Font " +
                  "x:Family=\"Swiss\" ss:Bold=\"1\"/>\r\n </Style>\r\n " +
                  "<Style     ss:ID=\"StringLiteral\">\r\n <NumberFormat" +
                  " ss:Format=\"@\"/>\r\n </Style>\r\n <Style " +
                  "ss:ID=\"Decimal\">\r\n <NumberFormat " +
                  "ss:Format=\"0.0000\"/>\r\n </Style>\r\n " +
                  "<Style ss:ID=\"Integer\">\r\n <NumberFormat " +
                  "ss:Format=\"0\"/>\r\n </Style>\r\n <Style " +
                  "ss:ID=\"DateLiteral\">\r\n <NumberFormat " +
                  "ss:Format=\"mm/dd/yyyy;@\"/>\r\n </Style>\r\n " +
                  "</Styles>\r\n ";
            const string endExcelXML = "</Workbook>";

            int rowCount = 0;
            int sheetCount = 1;
            /*
           <xml version>
           <Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
           xmlns:o="urn:schemas-microsoft-com:office:office"
           xmlns:x="urn:schemas-microsoft-com:office:excel"
           xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet">
           <Styles>
           <Style ss:ID="Default" ss:Name="Normal">
             <Alignment ss:Vertical="Bottom"/>
             <Borders/>
             <Font/>
             <Interior/>
             <NumberFormat/>
             <Protection/>
           </Style>
           <Style ss:ID="BoldColumn">
             <Font x:Family="Swiss" ss:Bold="1"/>
           </Style>
           <Style ss:ID="StringLiteral">
             <NumberFormat ss:Format="@"/>
           </Style>
           <Style ss:ID="Decimal">
             <NumberFormat ss:Format="0.0000"/>
           </Style>
           <Style ss:ID="Integer">
             <NumberFormat ss:Format="0"/>
           </Style>
           <Style ss:ID="DateLiteral">
             <NumberFormat ss:Format="mm/dd/yyyy;@"/>
           </Style>
           </Styles>
           <Worksheet ss:Name="Sheet1">
           </Worksheet>
           </Workbook>
           */
            excelDoc.Write(startExcelXML);
            excelDoc.Write("<Worksheet ss:Name=\"Sheet" + sheetCount + "\">");
            excelDoc.Write("<Table>");
            excelDoc.Write("<Row>");
            for (int x = 0; x < source.Tables[0].Columns.Count; x++)
            {
                excelDoc.Write("<Cell ss:StyleID=\"BoldColumn\"><Data ss:Type=\"String\">");
                excelDoc.Write(source.Tables[0].Columns[x].ColumnName);
                excelDoc.Write("</Data></Cell>");
            }
            excelDoc.Write("</Row>");
            foreach (DataRow x in source.Tables[0].Rows)
            {
                rowCount++;
                //if the number of rows is > 64000 create a new page to continue output

                if (rowCount == 64000)
                {
                    rowCount = 0;
                    sheetCount++;
                    excelDoc.Write("</Table>");
                    excelDoc.Write(" </Worksheet>");
                    excelDoc.Write("<Worksheet ss:Name=\"Sheet" + sheetCount + "\">");
                    excelDoc.Write("<Table>");
                }
                excelDoc.Write("<Row>"); //ID=" + rowCount + "

                for (int y = 0; y < source.Tables[0].Columns.Count; y++)
                {
                    System.Type rowType;
                    rowType = x[y].GetType();
                    switch (rowType.ToString())
                    {
                        case "System.String":
                            string XMLstring = x[y].ToString();
                            XMLstring = XMLstring.Trim();
                            XMLstring = XMLstring.Replace("&", "&");
                            XMLstring = XMLstring.Replace(">", ">");
                            XMLstring = XMLstring.Replace("<", "<");
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                           "<Data ss:Type=\"String\">");
                            excelDoc.Write(XMLstring);
                            excelDoc.Write("</Data></Cell>");
                            break;
                        case "System.DateTime":
                            //Excel has a specific Date Format of YYYY-MM-DD followed by  

                            //the letter 'T' then hh:mm:sss.lll Example 2005-01-31T24:01:21.000

                            //The Following Code puts the date stored in XMLDate 

                            //to the format above

                            DateTime XMLDate = (DateTime)x[y];
                            string XMLDatetoString = ""; //Excel Converted Date

                            XMLDatetoString = XMLDate.Year.ToString() +
                                 "-" +
                                 (XMLDate.Month < 10 ? "0" +
                                 XMLDate.Month.ToString() : XMLDate.Month.ToString()) +
                                 "-" +
                                 (XMLDate.Day < 10 ? "0" +
                                 XMLDate.Day.ToString() : XMLDate.Day.ToString()) +
                                 "T" +
                                 (XMLDate.Hour < 10 ? "0" +
                                 XMLDate.Hour.ToString() : XMLDate.Hour.ToString()) +
                                 ":" +
                                 (XMLDate.Minute < 10 ? "0" +
                                 XMLDate.Minute.ToString() : XMLDate.Minute.ToString()) +
                                 ":" +
                                 (XMLDate.Second < 10 ? "0" +
                                 XMLDate.Second.ToString() : XMLDate.Second.ToString()) +
                                 ".000";
                            excelDoc.Write("<Cell ss:StyleID=\"DateLiteral\">" +
                                         "<Data ss:Type=\"DateTime\">");
                            excelDoc.Write(XMLDatetoString);
                            excelDoc.Write("</Data></Cell>");
                            break;
                        case "System.Boolean":
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                        "<Data ss:Type=\"String\">");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("</Data></Cell>");
                            break;
                        case "System.Int16":
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            excelDoc.Write("<Cell ss:StyleID=\"Integer\">" +
                                    "<Data ss:Type=\"Number\">");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("</Data></Cell>");
                            break;
                        case "System.Decimal":
                        case "System.Double":
                            excelDoc.Write("<Cell ss:StyleID=\"Decimal\">" +
                                  "<Data ss:Type=\"Number\">");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("</Data></Cell>");
                            break;
                        case "System.DBNull":
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                  "<Data ss:Type=\"String\">");
                            excelDoc.Write("");
                            excelDoc.Write("</Data></Cell>");
                            break;
                        default:
                            throw (new Exception(rowType.ToString() + " not handled."));
                    }
                }
                excelDoc.Write("</Row>");
            }
            excelDoc.Write("</Table>");
            excelDoc.Write(" </Worksheet>");
            excelDoc.Write(endExcelXML);
            excelDoc.Close();
        }


        #region Convert to Dataset
        /// <summary>
        /// This will take anything that implements the ICollection interface and convert
        /// it to a DataSet.
        /// </summary>
        /// <example>
        /// CollectiontoDataSet converter = new CollectionToDataSet<Letters[]>(letters);
        /// DataSet ds = converter.CreateDataSet();
        /// </example>
        /// <typeparam name="T"></typeparam>
        public class CollectionToDataSet<T> where T : System.Collections.ICollection
        {
            T _collection;
            public CollectionToDataSet(T list)
            {
                _collection = list;
            }

            private PropertyInfo[] _propertyCollection = null;
            private PropertyInfo[] PropertyCollection
            {
                get
                {
                    if (_propertyCollection == null)
                    {
                        _propertyCollection = GetPropertyCollection();
                    }
                    return _propertyCollection;
                }
            }

            private PropertyInfo[] GetPropertyCollection()
            {
                if (_collection.Count > 0)
                {
                    IEnumerator enumerator = _collection.GetEnumerator();
                    enumerator.MoveNext();
                    return enumerator.Current.GetType().GetProperties();
                }
                return null;
            }

            public DataSet CreateDataSet()
            {
                DataSet ds = new DataSet("GridDataSet");
                ds.Tables.Add(FillDataTable());
                return ds;
            }

            private DataTable FillDataTable()
            {
                IEnumerator enumerator = _collection.GetEnumerator();
                DataTable dt = CreateDataTable();
                while (enumerator.MoveNext())
                {
                    dt.Rows.Add(FillDataRow(dt.NewRow(), enumerator.Current));
                }
                return dt;
            }

            private DataRow FillDataRow(DataRow dataRow, object p)
            {
                foreach (PropertyInfo property in PropertyCollection)
                {
                    dataRow[property.Name.ToString()] = property.GetValue(p, null);
                }
                return dataRow;
            }

            private DataTable CreateDataTable()
            {
                DataTable dt = new DataTable("GridDataTable");
                foreach (PropertyInfo property in PropertyCollection)
                {
                    dt.Columns.Add(property.Name.ToString());
                }
                return dt;
            }
        }
        #endregion Convert to Dataset
    }
}